Electromagnetic radiation offers many advantages over chemicals or heat as a decontaminant. Radiation is generally much less disturbing to the object being sterilized than either reactive oxidizers like chlorine or high temperatures. In addition, radiation can be applied with less labor and hence involve less risk. Unfortunately, germicidal ultraviolet radiation will not penetrate many common materials such as paper, plastics, fibers or metals. In contrast, high energy gamma rays will penetrate many objects, but require very large doses due to the small probability of interaction with the biological pathogens of interest, thereby further requiring massive shielding for safe use. X-ray radiation has been found to be a suitable decontaminant, is penetrating, and can be controlled simply and safely.
Design of the x-ray source for decontamination applications is qualitatively different than for conventional x-ray tubes used for imaging. Importantly, the x-ray emitting area needs to be large so that sharp shadows in the illuminated volume are avoided. If sharp, high contrast shadows occur, microscopic pathogens could escape from the irradiation and circumvent the desired sterilization. During operation, the x-rays are emitted from the outermost few microns of anode material which receives electron bombardment, so the electron beam must be tailored to impinge over the full surface of the anode to achieve the largest effective source size. To this end, the electric field guiding the electrons must be crafted to diverge from the cathode and intersect the anode uniformly, to the greatest extent possible. This technique of tailoring the electric field distribution in the x-ray source is further described in U.S. Patent Application Publication No. 2008/0056448 which is incorporated herein by reference. However, it remains desirable to develop an integrated device for delivery of soft x-ray radiation in such decontamination applications.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.